Looking at a publication entitled "Chevrolet Power Catalog - 6th Edition, 1988", I found a reference to a "tall" and a "short" deck block - both of which are big blocks. It is noted that the "short" version was used mainly in passenger cars, Corvettes, etc. while the "tall" version was used most frequently in heavy-duty trucks. Does anyone know if both of these blocks were 4-bolt mains or was the 4 bolt main used only on the Hi Performance ("short" version) and the "tall" version had a two bolt main (for low performance)? Also, does anyone know will such items as the crankshaft, camshaft, intake manifold and heads interchange on these blocks?
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the tall block i have seen were 4 bolt and
the intake manifold will not fit the std height block because it is wider as the heads are farther apart because of the deck height. the other parts of the tall block are the same except the piston have 4 rings instead of 3. we used the tall blocks to build stroker race engines like 511 cu in -
Re: Chevrolet Mark IV Big-Block V8, 427/435
Bob------
Yes, there were (and, still are) both "short deck" (9.8" crank centerline-to-deck) and "tall deck" (10.2"). I believe that the early versions (i.e. Mark IV) of the tall deck used both 2 and 4 bolt main configurations. However, I'm not 100% sure since I've never really studied these blocks---they were MD/HD truck only piece. NONE were ever originally used in passenger cars. The "tall deck" block is still manufactured today for SERVICE, but only in Gen VI configuration. In fact, the tall deck block is what's used for the 572 cubic inch "monster" big block engines. All current tall decks are 4 bolt main.
Most internal parts of the short deck and tall deck block engines will interchange. The exceptions are intake manifold, distributor, timing chain, and pistons.In Appreciation of John HinckleyComment
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Re: Chevrolet Mark IV Big-Block V8, 427/435
Joe/Clem,
Thank you for your respoonses - I appreciate all of your efforts. I have one more follow-on question re: this subject. Do you know if there are any "markings" or specific ways to tell the difference between the two blocks other than the height difference?Comment
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Re: Chevrolet Mark IV Big-Block V8, 427/435
Bob-----
The "short deck" blocks usually have "PASS" cast on them in the oil filter area and/or under the timing cover area. There may also be a "P" in the area of the casting number. I VERY VAGUELY recall that the "tall deck" blocks may have "TRUCK" cast on them, but I'm very uncertain of that. Don't get fooled into thinking that a block with a "T" on it represents "truck"; most big blocks of the pre-84 era had a "T" on them which denoted the Tonawanda foundry where they were cast.
Nothwithstanding the above, it's easy to differentiate between the 2 blocks. Look at the area between the waterpump cooling holes and the blcok deck surface. On a "short deck" block, this area will be about 3/4" thick; on a "tall deck" block it will be about 1-1/8".
The blocks can also be identified by casting number. "Short deck" and "tall deck" blocks do not share casting numbers.In Appreciation of John HinckleyComment
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10069282 366 cu in,10069284 427 cu in *NM*
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Re: Chevrolet Mark IV Big-Block V8, 427/435
a lot of the blocks had a 1/8" NTP thread in front of the intake manifold above the timing gear cover for oil supply to the air brake compressor.Comment
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Re: Chevrolet Mark IV Big-Block V8, 427/435
As mentioned, tall deck big blocks were truck only and short deck blocks were Pass car blocks.
ALLLLLLLLLLLLLLLLL of the tall deck blocks that I have ever seen (366 and 427) were only 4bolt main configuration. I've NEVER seen a 2bolt tall block. The 366s were commonly used in trucks such as school busses, delivery trucks (Coke, Coors, etc), dump trucks, etc. The 366 has never been a desireable engine because of the small bore and its cylinder walls are not thick enough to bore out to a useable diameter. BUUUUUUUUUUUUT, 366s DO HAVE one good redeeming quality, their main caps!!!!!!!!!!! Worn out 366s are usually scrapped and if you run across one, remove the main caps. They are great for converting pass car 2bolt blocks to 4bolt. ANY GOOD machine shop that does line boring/honing can easily do this for you. Its been a few years since I've had this done to a BB, but there was a time (when 366s were quite plentiful) that this process was pretty common. This is simple way to convert your 390hp/427 to a 435hp/427 configuration (whoops, sorry, this is the NCRS site, that's not allowed).Comment
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